Pack frame

ABSTRACT

A lightweight pack frame constructed of rigid polyvinyl chloride or like material including in one embodiment a molded U-shaped major support member, the legs of the &#39;&#39;&#39;&#39;U&#39;&#39;&#39;&#39; being joined by a curved, transverse extending support member which is adjustably mounted thereon to allow the size of the pack frame to be changed. A pair of flexible rods are end mounted to extend between the lower portion of the U-shaped major support member and the transverse support member such that they are bowed outwardly from the plane of the U-shaped support member to springingly hold a pack bag mounted on the frame away from the wearer&#39;&#39;s back.

United States Patent 1 Wood 1 May 22, 1973 PACK FRAME PrimaryExaminerGerald M. Forlenza [76] Inventor: Thomas E. Wood, 3863 42ndN.E., Fmsberg Seattle, wash 98105 AttorneyJohn O. Graybeal et al.

[22] Filed: Feb. 11, 1972 [57] ABSTRACT [21] Appl' 225,467 A lightweightpack frame constructed of rigid polyvinyl chloride or like materialincluding in one embodi- [52] US. Cl. ..224/25 A mm a molded p major ppmember, the [51] Int. Cl. ..A45t 3/00 g of the being joined y a curved,transverse [58] Field of Search ..224/25 A, 8 R, 8 A, extending supportmember which is adjustably 224/9, 11, 12 mounted thereon to allow thesize of the pack frame to be changed. A pair of flexible rods are end[56] References Cited mounted to extend between the lower portion of theU-shaped major support member and the transverse UNITED STATES PATENTSsupport member such that they are bowed outwardly 954,825 4/1910Schumacher ..224/12 from the plane of the U-shaped support member to3,223,300 12/1965 Moore et a1. 224/25 A springingly hold a pack bagmounted on the frame Babcock A away from the wearer's back 3,563,4312/1971 Pletz ..224/25 A 9 Claims, 9 Drawing Figures Patented May 22,1973 3,734,366

2 Sheets-Shoat 1 Patented May 22, 1973 2 Sheets-Sheet 2 FIG 9 PACK FRAMEBACKGROUND OF THE INVENTION 1, Field of the Invention This inventionrelates to pack frames used to assist in the carrying of a load on awearers back, and in particular, to lightweight, flexible pack framessuitable for recreational back packing.

2. Description of the Prior Art Wooden pack frames comprising a pair oflongitudinal supports interconnected by fixed transversely extendingdowels are known. Pack frames of this type are generally quite heavy andthis factor coupled with their rigidness and consequent failure to give"in response to movements of the wearer make them less than satisfactoryfor use on long hikes or when carrying heavy loads. Additionally, packframes of this type generally have no provision for maintaining the packbag mounted on the pack frame away from the wearers back, consequentlyoften allowing hard articles within the bag to dig into the back of thewearer.

Lightweight aluminum pack frames have substantially displaced woodenframes for use in recreational back packing, but the design of theseframes has remained basically similar to the design of wooden frames inthat generally a pair of longitudinally extending rodsare interconnectedby a plurality of curved transverse rods welded or otherwise fixedlymounted therebetween. In some designs of this type pack, a pair of smalldiameter metal rods are threaded longitudinally through the centralportions of the lateral supports to provide additional rigidity. Thepack bag is thus held away from the pack frame wearers back by means ofthe web of longitudinal and transverse supports between the majorlongitudinal supports. While the lightweight nature of the aluminumtubing used in the construction of this type frame inherently provides adegree of flexure to the frame, frames of this type are easily bent orbroken when dropped or otherwise heavily stressed.

BRIEF SUMMARY OF THE INVENTION The present invention relates to a packframe constructed of extruded plastic tubing material such as rigidpolyvinyl chloride. In one embodiment, a length of polyvinyl chloride ismolded to a substantially U- shape, with the legs of the U being curvedto a flattened S-shape along their length. A single transverse supportcomprising a curved hollow tube having a pair of fittings includingcylindrical portions extending transverse the tube is mounted on thelegs of the U-shaped member near the open end of the U by sliding andfastening the cylindrical portions of the fittings onto the legs of theU. The transverse support may be mounted at selected points along thelength of the legs to vary the operative vertical length of the frame toallow its comfortable use by wearers of differing size. A pair offlexible rods are end mounted to extend between the transverse supportand the U-shaped support such that they are bowed outwardly from theplane of the pack frame to springingly hold a pack bag mounted thereonaway from the back of the wearer.

The instant invention thus discloses a pack frame which maintains thepack bag away from the wearer's back in a novel manner which is simpleto construct,

requires a small number of inexpensive easily fabricated componentparts, is size adjustable, and is more flexible and more durable thanknown pack frames.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view of atypical pack frame constructed according to the instant invention.

FIG. 2 is a section view along lines 22 of FIG. 1, in cluding a pack bagshown in dashed line on the back of a wearer.

FIG. 3 is a section view along lines 33 of FIG. 1.

FIG. 4 is a section view along lines 44 of FIG. 1.

FIG. 5 is a perspective view of a typical pack frame constructedaccording to the instant invention, including a pack bag shown in dashedline mounted thereon.

FIG. 6 is a diagrammatic elevation view of a second typical embodimentof the pack frame of the instant invention wherein the pair of flexiblerods are mounted to extend between the opposite legs of the U-shapedsupport member.

FIG. 7 is a diagrammatic elevation view of a third typical embodiment ofthe pack frame of the instant invention wherein the pair of flexiblerods are bowed between spaced mounting points on each of the legs of theU-shaped support member.

FIG. 8 is a diagrammatic elevation view of a fourth typical embodimentof the instant invention wherein the longitudinal support memberscomprise a pair of laterally spaced tube members interconnected by avertically spaced pair of transverse supports.

FIG. 9 is a perspective view of a portion of the pack frame of theinstant invention including a height adjustable auxiliary transversemember mounted thereon.

DETAILED DESCRIPTION OF THE INVENTION Referring initially to FIG. 1, apack frame 10 is illus trated, basically comprising a U-shaped majorsupport member 12 including leg portions 14 and 16 and curved baseportion 18. Transverse support 20 is connected between legs 14 and 16near the open end of the U-shaped member by means of fittings 22, whichfittings include tubular recesses 24 in which member 20 is end mountedand hollow cylindrical portions 26 which are slidable on legs 14 and 16and mountable at a selected position by means of pins 27 in a manner tobe described more completely with reference to FIG. 3. Flexible rods 28and 30 are end mounted in cooperatingly sized holes 32 and 34 intransverse support 20 and legs 14 and 16 respectively. Flexible rods 28and 30 are bowed prior to their mounting in holes 32 and 34, and as bestseen in FIG. 2, these rods remain bowed after mounting such that theyact to hold pack bag 36 away from the back of the wearer. It will beunderstood that in FIG. 2, flexible rods 28 and 30 are shownsubstantially in the position that they assume upon mounting, and thatthese rods are compressed a portion of the distance toward the back ofthe wearer when pack bag 36 is loaded thereby allowing the load to becarried essentially vertically with the center of gravity of the pack.

Conventional shoulder straps 38 are mounted on the pack frame to extendbetween pin mounts 40 on transverse rod 20 and pin mounts adjacentbottom portion 18 of the U-shaped support frame. The pin mountsillustrated in FIG. 1, comprise a pin member which is insertable throughaligned holes extending through the tubular pack frame at selectedpoints and held therein by means of a wire clip inserted through a holein the shank of the pin.

Referring now to FIG. 3, a second form of pin comprising a head portion44 and a split shank portion 46 having ridge portions 48 designed toprevent inadvertent or unintentional removal of the pin is disclosed. Itwill be understood that this pin fastener may be satisfactorilyconstructed from various plastic materials, including those from whichthe frame components themselves are constructed.

Conventional pads 50 are positioned at desired locations longitudinallyalong legs 14 and 16 and held thereon by means of buckles 52 or the liketo cushion legs 14 and 16. As is best seen in FIG. 2, legs 14 and 16 aremolded to what may be described as a flattened S-shape which conformsgenerally to the spine of a wearer. Pads 50 are generally positioned atthe most likely points of contact between the wearer and legs 14 and 16,usually in the small of the wearers back and slightly below theshoulders as illustrated.

Referring now to FIG. 3, the means by which transverse support rod 20may be adjusted to selected longitudinal positions on legs 14 and 16 isdisclosed. As shown, leg 14, and leg 16 also although not shown,includes a plurality of aligned holes 52, 54 and 56 extendingtherethrough and longitudinally spaced therealong. It has been foundthat three sets of holes spaced over a distance of three inches providesa range of adjustment sufficient for most users. Cylindrical portion 26of fitting 22 includes a pair of aligned holes 58 having substantiallythe same diameter as holes 52, 54 and 56 in leg 14 and suitable forreceiving the fastening pin. It will be understood that upon removal ofthe fastening pins, fittings 22 may be moved upwardly or downtightenedto the point where they tend to draw legs 14 and 16 inwardly tocounteract the loading force of the bag.

As illustrated in FIG. 5, legs 14 and 16 are provided with verticallyspaced sets of holes 60, 62, 64 and 66 in addition to the holes providedfor vertical adjustment of transverse member 20. Pack bag 36 is mountedon the pack frame by means of pins 27 which extend through appropriatelysized grommets on the rear portion of the pack bag and thence throughthe three uppermost sets of holes 60, 62 and 64. While it is usuallypreferred to carry a pack bag high on a pack frame in order that theweight of the bag is thrown onto the wearers shoulders rather than thelower portion of the wearers back, it will be understood that the packbag may also be mounted in a similar manner on sets of holes 62, 64 and66 where it is desired to fasten additional materials to the top portionof the pack frame,

wardly on leg 14 until holes 58 are aligned with one of the sets ofholes 52, 54 and 56 as desired, at which time the connecting pin may beinserted. This construction provides easy adjustment as well as ease oforiginal fabrication.

Referring now to FIG. 4, the mounting of flexible rod 30 in acooperatingly sized hole 32 in transverse rod 20 is disclosed. Duringfabrication, one end of the flexible rod is merely inserted in one ofthe holes 32 or 34, and the rod bowed outwardly until the free end maybe inserted in the remaining hole. As illustrated, rod 30 extendsthrough hole 32 and abuts against the internal wall of tube 20 oppositethereto, and it will be understood that the compression force applied tobow rods 28 and 30 during fabrication of the pack frame maintains theserods firmly in holes 32 and 34. FIG. 4 discloses rod 30 to beconstructed of thick walled hollow tubing, and while this configurationis preferred, a solid flexible rod may be substituted therefor withlittle additional pack frame weight gain. As illustrated, holes 32 aredrilled through one wall of tube 20 on a line radial to the center lineof the tube but at an angle to a vertical plane bisecting the tubelongitudinally.

Referring now to FIG. 5, it will be seen that transverse support member20 and the lower portion 18 of the U-shaped major support member arecurved to generally correspond to the curve of the wearers back andwaist or hips respectively, thus preventing shifting of the pack fromside to side during climbing. Transversely extending members 18 and 20impart a degree of lateral stability to legs 14 and 16, however, whenbag 36 is heavily loaded the central portions of legs 14 and 16 tend tobe bowed laterally outward. Pads 50 may be such as when using heightadjustable transverse support 68 discussed hereafter with reference toFIG. 9.

A conventional pack belt 70 is shown mounted on the pack frame in holes66 by means of pins 27. As is known, belts of this type may be used tolift the weight of the pack onto the wearers hips and thus, at leastpartially, off of the wearers shoulders to increase the backpackerscomfort during long hikes.

Referring now to FIG. 6, a second embodiment of the pack frame of theinstant invention is disclosed wherein flexible rods 28 and 30 are bentto extend between holes 34 in the lower portions of legs 14 and 16 andholes 72 in the upper portions of legs 14 and 16 just below transversesupport 20. It will be understood that in this configuration, flexiblerods 28 and 30 are bowed laterally outward from the plane of the packframe to hold a pack bag mounted thereon away from the wearers back inthe same manner disclosed above with reference to FIG. 2.

FIG. 7 discloses still another embodiment of the instant inventionwherein each of the flexible rods 28 and 30 are mounted in holes 34 inlegs 14 and 16 and then bent in a semicircular configuration such thatthe distal end of each rod is mounted in hole 72 on the same leg 14 or16 of the pack frame.

Referring now to FIG. 8, an additional embodiment of the instantinvention wherein the pack frame comprises a pair of individual verticalsupport members 74 and 76 interconnected by a vertically spaced pair oflateral support members 20 and 78, is illustrated. While not shown inthis view, it will be understood that legs 74 and 76 may be curved alongtheir length to the flattened S-shape of legs 14 and 16. Flexible rods28 and 30 are shown bowed in the configuration of FIG. 5, but it will beunderstood that the configurations of FIGS. 6 and 7 may also be used inthis configuration. Further, other curvatures of rods 28 and 30 capableof satisfactorily carrying out the purpose of maintaining the pack bagaway from the wearers back and usable with either of the embodiments ofFIGS. 1 or 8 are considered to be within the scope of this invention.

As has been mentioned briefly hereabove, transverse rod 20, and alsotransverse rod 78, are mounted end wise in tubular recesses 24 infittings 22. Members 20 and 78 are held within recesses 24 by means ofregular thermosetting glue or plastic cement of a type suitable for usewith the plastic material chosen to construct the pack frame.

While it has been found that a standard rigid polyvinyl chloride tubematerial, preferably of the schedule 40 type 2 class is mostsatisfactory for use in constructing the pack frames of the instantinvention from the standpoint of both ruggedness and low cost, othermaterials such as ABS which has an attractive high gloss surface lusterand is available in a wide variety of colors, as well as a tough butflexible polyethylene may also be used. The difficulty of gluingpolyethylene thereby requiring the use of welding or machine fasteningto join the separate members of the frame is, however, a disadvantage ofthis material. A polycarbonate material such as that sold under thetrademark Lexan which resists deformation under long-term loading aswell as having a high surface gloss and good temperature characteristicsmay also be most satisfactorily used, however the high cost of thismaterial is a disadvantage from the marketing point of view. A polyvinylchloride having a specific gravity of approximately 1.5, a tensilestrength between 8,000 and 10,000 psi, an impact strength of about ft.lbs/in. notch and a hardness of about 83 Shore D has proven verysatisfactory in constructing pack frames made according to thisinvention.

One advantage of all of the above materials for use in construction of apack frame, is that their resistance to permanent deformation is muchgreater than that of the presently used aluminum thereby providing apack frame having substantially the same weight as aluminum but which issignificantly more durable. One frame constructed according to theteachings of the instant invention out of the above described rigidpolyvinyl chloride has been loaded with a 40 pound pack bag and droppedrepeatedly at a variety of angles from a height of 6 feet withoutsuffering any damage. Additionally, frames constructed of the abovematerials will flex and twist with the wearer thus making these framessubstantially more comfortable than previously known pack frames,particularly those capable of being constructed at the relatively lowcost of the instant pack frame.

Referring now to FIG. 9, an accessory transverse support rod 68, wherebythe size and consequent load carrying ability of the instant pack framemay be increased is disclosed. Curved transverse support 68 includes apair of leg portions 80 and 82 which are sized to be insertable withinthe hollow legs 14 and 16 of the pack frame respectively after removalof end snap caps 84 (FIG. 5). As illustrated, transverse member 68 maybe disposed in a first downward position wherein legs 80 and 82 arepositioned substantially entirely within the top portion of legs 14 and16 and in this position member 68 primarily acts to increase thetransverse rigidity of the pack as may be desired, for example, whencarrying exceptionally heavy'loads. Transverse member 68 is held inposition by means of pins 27 which extend through holes 60 in pack framelegs 14 and 16 and through cooperating aligned holes 86 in legs 80 and82. To extend the vertical length of the pack frame, transverse member68 may be moved upwardly such that holes on the lower portions of legs80 and 82 may be pinned through holes 60 as shown in dotted line in FIG.9. In this configuration, a sleeping bag or the like may be carried ontop of a pack bag mounted as shown in FIG. 5.

In one embodiment of the instant invention, a section of rigid polyvinylchloride tubing having a length of 76 inches and an inside diameter ofapproximately fiveeighths of an inch was heat molded in a jig to the Ushape disclosed in FIG. 5. Prior to heat molding, a piece of rope wasinserted within the hollow tubing to prevent collapse of the tube duringheating. In like manner, a 13 inch length of tubing of like diameter wasmolded to form transverse support member 20. Member 20 was then gluedwithin recesses 24 of standard fittings 22 and this element was slippedover the ends of legs 14 and 16 and fastened through one of the sets ofholes 52, 54 or 56 in the manner discussed heretofore. These holes, aswell as sets of holes 60, 62, 64 and 66 may have a diameter ofone-fourth to threesixteenths of an inch and may be formed in aconventional manner such as through the use of a set of ganged drills.Thick walled flexible tubing material having a length of 25 ii inchesand a inch outside diameter was then mounted in correspondingly sizedholes 32 and 34 and bowed to extend laterally outward from the plane ofthe pack frame to hold a pack bag mounted thereon away from the wearersback.

The invention may be embodied in other specific forms without departingfrom the spirit or central characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore to be embraced therein.

What is claimed is:

l. A pack frame for supporting a pack bag comprising:

a molded substantially U-shaped major support member including a pair ofupstanding parallel legs and a curved bottom portion;

a transverse support member curved generally in the shape of the bottomportion of said U-shaped major support member and mounted to extendbetween said upstanding legs at a distance from said curved bottomportion; and

a pair of flexible rods end mounted in cooperatingly sized holes in thelegs and the transverse member to extend between the legs of said majorsupport member and said transverse support member and resiliently bowedto support said pack bag at a distance outwardly from said major andtransverse support members.

2. The pack frame of claim 1 wherein said upstanding parallel legsinclude a plurality of longitudinally spaced pairs of holes, saidtransverse member mountable by means of pins positioned to extendthrough said transverse member and through selected pairs of said holesto vary said distance between said transverse member and said curvedbottom portion of said major support member.

3. The pack frame of claim 1 wherein said U-shaped major support member,said transverse support member and said flexible bowed rods areconstructed of single unitary pieces of rigid polyvinyl chloride havinga specific gravity of approximately 1.5, a tensile strength ofapproximately 9,000 psi, an impact strength of about 15 ft.lbs/in. notchand a hardness of approximately 83 Shore D, to obtain a pack framehaving high degree of flexibility.

4. The pack frame of claim 1 wherein said pair of flexible rods are endmounted in cooperatingly sized holes in said pair of upstanding parallellegs.

5. The pack frame of claim 1 wherein said transverse support memberincludes end mounted pairs of fittings having transversely extendingcylindrical portions, said transverse portions sized to receive saidupstanding parallel legs, and means removably interconnecting saidfittings and said upstanding legs at selected points therealong.

6.- The pack frame of claim 1 including a second transverse supportmember including a pair of downwardly extending leg portions slidablymountable within said pair of upstanding parallel legs.

7. An all plastic flexible pack frame for supporting a pack bagcomprising:

a heat molded substantially U-shaped major support member having a pairof upstanding parallel legs and a curved bottom portion formed from asingle hollow length of polyvinyl chloride tubing;

a curved transverse support member mounted to extend between the legs ofsaid U-shaped major support member and slidably adjustable thereon; and

a pair of flexible rods end mounted on and extending between theparallel legs of said U-shaped support member and said transversesupport member and bowed to extend outwardly from the plane of saidvU-shaped support member and said transverse support member to supportsaid bag.

8. A plastic pack frame for supporting a pack bag comprising:

' a first pair of vertically extending laterally spaced support membersmolded along their length to a flattened S configuration;

a second pair of vertically spaced curved support members extendingtransversely between said first pair of vertically extending supportmembers and including means for adjustably mounting said curved supportmembers thereon; and

a pair of flexible rods end mounted on and extending between one of saidtransversely extending curved support members and said pair ofvertically extending support members and bowed to extend outward fromthe plane of said support members to resiliently support a pack bag.

9. The plastic pack frame of claim 8 wherein said pair of verticallyextending support members include a plurality of vertically spacedholes, at least one of said vertically spaced support members mountableby means of pins positioned to extend through said vertically spacedsupport member and through selected pairs of said holes to vary thevertical spacing between said vertically spaced support members.

1. A pack frame for supporting a pack bag comprising: a moldedsubstantially U-shaped major support member including a pair ofupstanding parallel legs and a curved bottom portion; a transversesupport member curved generally in the shape of the bottom portion ofsaid U-shaped major support member and mounted to extend between saidupstanding legs at a distance from said curved bottom portion; and apair of flexible rods end mounted in cooperatingly sized holes in thelegs and the transverse member to extend between the legs of said majorsupport member and said transverse support member and resiliently bowedto support said pack bag at a distance outwardly from said major andtransverse support members.
 2. The pack frame of claim 1 wherein saidupstanding parallel legs include a plurality of longitudinally spacedpairs of holes, said transverse member mountable by means of pinspositioned to extend through said transverse member and through selectedpairs of said holes to vary said distance between said transverse memberand said curved bottom portion of said major support member.
 3. The packframe of claim 1 wherein said U-shaped major support member, saidtransverse support member and said flexible bowed rods are constructedof single unitary pieces of rigid polyvinyl chloride having a specificgravity of approximately 1.5, a tensile strength of approximately 9,000psi, an impact strength of about 15 ft.lbs/in. notch and a hardness ofapproximately 83 Shore D, to obtain a pack frame having high degree offlexibility.
 4. The pack frame of claim 1 wherein said pair of flexiblerods are end mounted in cooperatingly sized holes in said pair ofupstanding parallel legs.
 5. The pack frame of claim 1 wherein saidtransverse support member includes end mounted pairs of fittings havingtransversely extending cylindrical portions, said transverse portionssized to receive said upstanding parallel legs, and means removablyinterconnecting said fittings and said upstanding legs at selectedpoints therealong.
 6. The pack frame of claim 1 including a secondtransverse support member including a pair of downwardly extending legportions slidably mountable within said pair of upstanding parallellegs.
 7. An all plastic flexible pack frame for supporting a pack bagcomprising: a heat molded substantially U-shaped major support memberhaving a pair of upstanding parallel legs and a curved bottom portionformed from a single hollow length of polyvinyl chloride tubing; acurved transverse support member mounted to extend between the legs ofsaid U-shaped major support member and slidably adjustable thereon; anda pair of flexible rods end mounted on and extending between theparallel legs of said U-shaped support member and said transversesupport member and bowed to extend outwardly from the plane of saidU-shaped support member and said transverse support member to supportsaid bag.
 8. A plastic pack frame for supporting a pack bag comprising:a first pair of vertically extending laterally spaced support membersmolded along their length to a flattened ''''S'''' configuration; asecond pair of vertically spaced curved support members extendingtransversely between said first pair of vertically extending supportmembers and including means for adjustably mounting said curved supportmembers thereon; and a pair of flexible rods end mounted on andextending between one of said transversely extending curved supportmembers and said pair of vertically extending support members and bowedto extend outward from the plane of said support members to resilientlysupport a pack bag.
 9. The plastic pack frame of claim 8 wherein saidpair of vertically extending support members include a plurality ofvertically spaced holes, at least one of said vertically spaced supportmembers mountable by means of pins positioned to extend through saidvertically spaced support member and through selected pairs of saidholes to vary the vertical spacing between said vertically spacedsupport members.